Cardiac stimulation systems commonly include a pulse-generating device, such as a pacemaker or implantable cardioverter/defibrillator that is electrically connected to the heart by at least one medical electrical lead. A medical electrical lead delivers electrical pulses emitted by the pulse generator to the heart, stimulating the myocardial tissue via electrodes included on the lead. Cardiac signals may also be sensed by lead electrodes and conducted, via the lead, back to the device to monitor the electrical activity of the heart. These leads are coupled to the devices via connector terminals carrying one or more contact surfaces, which are in turn coupled to corresponding lead electrodes by elongate conductors extending within the lead.
In many instances a coiled wire or wires form lead conductors and, in order to maintain a low profile, a single coiled conductor of a lead may include multiple wire filars forming independent circuits between multiple electrodes and corresponding connector contact surfaces. In order to maintain electrical isolation between the independent filar circuits of a coiled conductor, an insulative layer is formed about one or more of the filars. In order to electrically couple an insulated wire filar to an electrode, and to a corresponding connector contact, portions of the insulative layer are removed to expose an electrically active surface of the conductor.
Although embodiments of the present invention have been introduced in the context of cardiac stimulation systems, it should be understood that the invention is not so limited, being applicable for medical electrical leads applied for any therapeutic and/or diagnostic purpose.